This invention relates generally to alternators and, more particularly, to alternators intended for use in portable power generating equipment.
Portable power generating equipment typically consists of an internal combustion engine coupled to a generator or alternator that converts the mechanical energy of the engine electrical energy. Although both generators and alternators rely on a changing magnetic field to induce currents in an electrical winding, alternators, which provide certain mechanical advantages such as the elimination of heavy current-carrying brushes, are best suited for use in portable power generators.
Alternators can use either electrical field windings or permanent magnets to develop the changing magnetic field. Permanent magnets are advantageous in that they totally eliminate the need for brushes and conserve power that would otherwise be lost in the field windings.
Several factors need to be considered in designing a permanent magnet alternator intended for use in a portable power generating apparatus. Although known power generating devices are "portable" in a general sense, such devices frequently weigh over 100 pounds and require two people to lift and carry. Much of the weight and bulk comes from the alternator itself which, along with the internal combustion engine, forms the heart of the power generating device. A constant goal in alternator design is to increase the power output capability without a corresponding increase in alternator bulk and weight.
Another factor that needs to be considered in alternator design is cost. Because the alternator frequently represents a significant fraction of the overall cost of a portable power generating device, alternator cost, particularly in the consumer market, can have a profound effect on the overall commercial success or failure of a particular power generating device. Manufacturing and labor costs, as well as material costs, all affect the final, overall cost of an alternator and the power generating device in which it is incorporated.
Still another factor to be considered is the overall efficiency of an alternator. For a given power output, efficient alternators can be turned by smaller, lighter and more inexpensive engines. This, again, can have a significant effect on the overall commercial success or failure of a portable power generating device.
In view of the foregoing, it is a general object of the present invention to provide a new and improved permanent magnet alternator for portable power generating devices.
It is a further object of the present invention to provide a permanent magnet alternator that is compact, lightweight and efficient in operation.
It is a still further object of the present invention to provide a permanent magnet alternator that is economical in manufacture.